Mail on subday

I think you meant to say "mail on Sunday".

In many countries, including the United States, Sunday is considered a day of rest and is not typically a day for mail delivery. In the US, the United States Postal Service (USPS) does not deliver mail on Sundays, except for certain packages and priority mail items.

However, some private courier services, such as UPS and FedEx, may deliver packages on Sundays, depending on the service level and destination.

If you're expecting a package or mail delivery on a Sunday, it's best to check with the sender or the shipping carrier to confirm their delivery schedule and any potential delays.